1. Field of the Invention
This invention concerns a method for determining the content of water soluble strong acids in air in which the air is passed in contact with a watery liquid and then again separated from the liquid. The invention further concerns an apparatus for determining the content of water soluble strong acids in air, in which in a first stage air is passed in contact with a watery liquid and the strong acids are dissolved therein.
2. Description of Related Art
The analysis of trace elements in the atmosphere is becoming more important with the air pollution that is always becoming more problematic. The strong acids, for example nitric acid, sulfuric acid and hydrochloric acid, which are either admitted directly into the air or arise in the air as products of pollution emissions, play a particularly strong role in the problems of cleaning the air. Because of their high solubility in water, the acids dissolve in precipitation and because of their great dissociation constants (K.sub.s &gt;1 mol/l) they dissociate completely into the corresponding anions and H.sub.3 O.sup.+. Finally they reach the ground with the precipitation ("acid rain"). Measurements and investigations for determining the concentration of the water soluble strong acids in the air are of importance for estimating the acidity that appears in precipitation and, particularly, the determination of this concentration of strong acids in air leads to conclusions concerning the transformation of air pollution and also makes possible the development of strategy for reducing the acid content of rain. It is not so much the identification of particular acids that is of importance, but rather the determination of the aggregate content of as H.sub.3 O.sup.+ ions present in a volume of air and capable of being set loose when taken up in water. These magnitudes can be designated as potential acidity.
In order to determine trace elements and monitor them, it is not only important that the measuring process should be sufficiently accurate. The measuring process should also be economic to install, for example, in measuring vehicles, should be simple and should be capable of being carried out with simple equipment. This applies in the present case, since investigations need to be carried out also in upper regions of the atmosphere, where it is desirable for the measurement apparatus to be installed in a balloon sonde.
The presently known measurement processes for determining acids in air are concerned with the determination of the individual components and involves a high cost in instrumentation and operative timing. They are capable of being installed only on the ground or at best in airplanes and in large dirigibles or balloons. The known simple measurement processes for determining acidity are usable only in a discontinuous manner for analysis of precipitation that has already fallen.